Longevity

Now consider the possibility of super longevity, i.e. living as long as possible. Think of it as more healthy years rather than more “old” years.

A simplistic and rather typical view of population growth is that more people means less food per person. But population and food supply do not have a simple linear relationship if the relationship is viewed over time. We are creative minds who work together to improve our condition, so more people can very well mean more food. Other arguments against longevity range from, “It’s up to God when I die”, to “I’d get bored if I lived so long”, to “Being ‘old’ for so long would be horrible”, to the most popular fear of overpopulation.

Longevity does not mathematically effect population. The amount of offspring per couple is what affects population. The poor tend to have more offspring for various practical reasons, so longevity is best viewed as an economic issue. Healthy societies that are better off economically tend to have less offspring per couple, and therefore their population growth might taper off and even decline over time. Healthy economies tend to attract large influxes of immigrants, but can better handle large populations in general.

Think of how many more healthy years we experience now with our current average lifespan of 80 years than we did when 25 years was the average lifespan. Longevity allows more time to gain experience and wisdom and to connect with following generations to properly pass along lessons learned. Ultimately some will choose to make another giant leap for humankind and permanently migrate outside of the Earth-Moon system. Long lives will suit us better for the exceedingly long journeys that we will want to take.

As little conscious chunks of the universe, with an ever expanding curiosity, we will need long and healthy lifespans as we chip away at our knowledge gaps as we get to know our “God”, the Cosmos.

Hello Steve. Sorry for the delay. I’m glad you brought that up, because I really should change that to “population growth rate” which is how I refer to it in the book!

Longer life spans do not affect population growth to the extent that people imagine. The population growth rate is determined by how many offspring we have and at what age we have them, rather than how long we live.

Imagine if every woman waited until they were in their 40’s to have children, and their children also waited until their 40’s, and on down the line. The population growth rate would slow tremendously. If everyone had children at 18 (and assuming the same number of children were born as in the 40’s example) it would speed up. Whether everyone in either scenario died at 50 or 120 would make no difference in the population growth rate.

If people all suddenly started living until 500 years on average and everything else stayed roughly the same, the population would initially grow in a leap as people are born in the first 500 year period; however, the population would resume its previous growth rate as the older generation started expiring. If it were possible, and everyone also decided to wait until age 400 to have 2 children each, imagine how slowly the population would grow! By contrast, if people lived to be only 34 years on average and had five offspring per woman, the population would grow exponentially out of control.

Simply stated, when it comes to the population growth rate it doesn’t matter all that much how long people live after they are done reproducing.

The “population equation” that is most commonly used is:

x = rx (1-x)

And in English:

next year’s population = growth rate * this year’s population * (1 – this year’s population)

Notice that it does not include any values or parameters for “lifespan”.